Neutral Pentacoordinate Silicon(IV) Complexes with Silicon–Chalcogen (S, Se, Te) Bonds

Abstract

The neutral pentacoordinate silicon(IV) complexes 1 (SiS2ONC skeleton), 2 (SiSeSONC), 3 (SiTeSONC), 6/9 (SiSe2O2C), 7 (SiSe2S2C), and 8/10 (SiSe4C) were synthesized and structurally characterized by using single-crystal X-ray diffraction and multinuclear solid-state and solution-state (except for 6-9) NMR spectroscopy. With the synthesis of compounds 1-3 and 6-10, it has been demonstrated that pentacoordinate silicon compounds with soft chalcogen ligand atoms (S, Se, Te) can be stable in the solid state and in solution.

Four‐, Five‐, and Six‐Coordinate Silicon(IV) Complexes: Reactivity of the Donor‐Stabilized Silylenes [iPrNC(Ph)NiPr]2Si and [iPrNC(NiPr2)NiPr]2Si Towards Me3SiN3 and PhSCH2N3

“…This Si–N distance is significantly longer than that of the Si–N=CH 2 moiety of the four‐coordinate silicon(IV) complex 19 [1.735(2) Å] (Scheme ),[1d] which correlates with the different silicon coordination numbers six ( 5a , 5b ) and four ( 19 ). The Si–SPh distances of 5a [2.2931(10) Å] and 5b [2.2906(10) Å] are somewhat longer than those of the four‐coordinate silicon(IV) complexes 15 [2.1462(8) Å] and 19 [1d] [2.1610(19) Å] and the five‐coordinate silicon(IV) complex 20 [2.1881(6) Å], which is also in agreement with the different silicon coordination numbers (six versus four and five) (Scheme ).…”

Cationic Five‐Coordinate Bis(guanidinato)silicon(IV) Complexes with SiN4El Skeletons (El=S, Se): “Heterolytic Activation” of S−S and Se−Se Bonds

“…The signal at δ =191.8 ppm is assigned to the cation of 5 . This isotropic 77 Se NMR chemical shift is comparable with those of compound 10 , which also contains a silicon‐bound SePh group (solid state, δ ( 77 Se)=181.9 ppm; solution (CD 2 Cl 2 ), δ ( 77 Se)=161.6 ppm) . The 1 J ( 29 Si, 77 Se) coupling constants of 10 in the solid state (121 Hz) and in solution (132 Hz) also compare well with that observed for 5 (145 Hz).…”

Ylenes in the MII→SiIV (M=Si, Ge, Sn) Coordination Mode

“…Tacke et al presented a rare example with I and S atoms attached to a pentacoordinate silicon atom, [4] and only recently this group reported pentacoordinate Si complexes which comprise four Se atoms or even a Te atom attached to the silicon atom. [5] In spite of these promising pioneering results, the investigation of heavier Group 14 lone pair donors (germylenes and stannylenes) in the Si coordination sphere remains an open task. [6] Although the heavier ylenes GeCl 2 and SnCl 2 are isolable, and the portfolio of isolable silylenes did enjoy a notable growth in recent years, [7] only carbenes were reported as Group 14 ylene ligands in the coordination sphere of hypercoordinate Si atoms so far.…”